1. Field of the Invention
The present invention is concerned with the recovery of lithium and boric acid from lithium and boron-containing brines and, more particularly, with a brine sulfate salting-out process for lithium recovery which may be preceded or followed by a brine strong acid treatment to yield boric acid.
2. Description of the Prior Art
Generally, small but commercially significant quantities of lithium may be found in certain industrial effluents and in many of the salt lakes around the world. Typically, the small quantities of lithium are concentrated by various methods and then recovered by known precipitation or separation means.
Because of the economics in concentrating large quantities of brine, solar pond evaporation in combination with other treatments are commonly utilized in recovering the lithium values. U.S. Pat. No. 3,268,289 describes a system for precipitating sodium sulfate from Great Salt Lake brine and utilizing the sulfate to selectively remove magnesium salts therefrom. Further evaporation of the brine results in increased concentration of lithium chloride which facilitates its recovery.
A solar pond management system for recovering lithium values is disclosed in U.S. Pat. No. 3,342,548. This patent coordinates seasonal weather patterns with the flow of brine between solar ponds and the selective precipitation of magnesium, potassium and sodium salts. The purpose of the system is to increase the level of lithium chloride and diminish the level of magnesium chloride for easier recovery of the lithium salt.
In U.S. Pat. No. 3,537,813 a metal halide such as ferric chloride is added to lithium-containing brines along with an acid to form an insoluble lithium complex. The lithium is subsequently extracted with an organic solvent and phase separation treatment.